1. Field of the Invention
The present invention is generally in the field of electronic circuits and systems. More specifically, the present invention is in the field of electronic communications circuits and systems.
2. Background Art
Mixers are typically used in transmitting systems to, for example, up-convert an input baseband or intermediate frequency (IF) signal prior to transmission. In a conventional mixing circuit, the mixer itself may be paired with a power amplifier. In that configuration the mixer output may be fed into a discrete power amplifier to impart a desirable transmission power level to the up-converted transmission signal. As is known in the art, however, the performance of power amplifiers involves a trade-off between efficiency and the linear response of the amplifier, where improvement in one characteristic results in an undesirable deterioration of the other.
The consequences of the irreconcilability of linearity and efficiency in a power amplifier has significant implications for mobile communication devices utilizing a transmitting system, for example, as part of a transceiver. Because mobile communication devices, such as mobile telephones, typically rely on a battery for power, inefficiency in a power amplifier undesirably shortens battery life. Utilizing a high efficiency power amplifier, on the other hand, while advantageously enhancing battery life, may, due to its reduced linearity, lead to undesirable transmission anomalies, and in extreme cases may result in unintended transmission at frequencies not authorized for public use by the Federal Communication Commission (FCC).
Thus, there is a need in the art for a solution capable of compensating for the performance limitations of a conventional transmitter, that enables up-conversion and amplification of a transmission signal while advantageously providing improved linearity and conserving operational power.